For instance, an LED lighting apparatus is known that includes (i) a power supply device that receives power supply from a DC-DC converter for converting a DC power supply voltage into a predetermined DC voltage and includes LED driving circuits connected in parallel and to the output of the DC-DC converter and (ii) LED luminaires respectively connected to the LED driving circuits. As a device other than the LED luminaires, a sequencer or other equipment may be further connected in parallel to the power supply device. Thus, a predetermined DC voltage is supplied from the DC-DC converter to the device other than the LED luminaires.
In the LED lighting apparatus, if the LED driving circuits strobe the LED luminaires by random triggers, coincidence of light emission of each LED luminaire results in momentary excess output. This decreases a voltage supplied from the DC-DC converter. Thus, a voltage necessary for driving the sequencer cannot be supplied from the DC-DC converter, thereby stopping the operation of the sequencer. This may cause a serious problem in another device controlled by the sequencer.
Patent Literature 1 presents problems relating to excess output in an LED lighting apparatus in which LED luminaires are connected in parallel to a power supply device including an AC-DC converter for converting a commercial AC voltage into a predetermined DC voltage, instead of a DC-DC converter.
However, the objective of Patent Literature 1 is to prevent an excess current from flowing at the time of occurrence of the excess output, thereby preventing elements constituting the AC-DC converter from breaking down. Thus, if the excess output occurs, the output voltage of the AC-DC converter is decreased.
Thus, if a device other than the LED luminaires is connected to the AC-DC converter also in the power supply device in Patent Literature 1, the occurrence of the excess output results in a decrease in voltage supplied to the device and stops the function of the device. That is, the above problems cannot be solved by the technique of Patent Literature 1.